Description
The ringing FlexiSLIC™ PBL 387 72/1 Subscriber Line Interface Circuit (SLIC) is a 90 V bipolar integrated cir cuit for use in short loop applications. The PBL 387 72/1 SLIC has been optimized for low power consumption, low total line interface cost and for a high degree of flexibility in various applications.
The PBL 387 72/1 SLIC supplies a balanced, sinewave or trapezoidal ringing signal of up to 81 VPeak (85 V DC supply) to the subscriber line across a load of up to 5REN. The PBL 387 72/1 supplies programmable constant current to the subscriber loop, sourced from the talk battery. The On-Hook line voltage of 43 V to 56 V is derived from the battery. All battery switching is internal to the device and is automatic. To further reduce power consumption the automatic gain control for the ring signal (AGC-R) keeps the level always adjusted to the maximum, that can be sourced from the available battery.
The SLIC incorporates loop current, ground key and ring-trip detection functions. The PBL 387 72/1 is compatible with loop start and ground start signalling. Two- to four-wire and four- to two-wire voice frequency (vf) signal conversion is accomplished by the SLIC in conjunction with a standard codec. The line terminating impedance and balance impedance is programmable and may be complex or real for worldwide compliance.
Longitudinal balance specifcations and other device characteristics are in compliance with Telcordia (Bell-core) and ITU-T requirements.
Tip and ring voltages are UL-1950 compliant; i.e. no two-wire line voltage exceeds 56 V. The PBL 387 72/1 SLIC is packaged in a surface mount 28-pin SOIC package.

KEY FEATUREs
• On-chip ringing generation
   - Balanced, up to 81 VPeak
   - Any waveform
   - 5REN ringing load
   - Automatic gain control of ring signal (AGC-R)
   - Short circuit safe
• Low on-hook power consumption in Active
   State (65 mW @ VBat = -80 V)
• Automatic current controlled battery
   switching between on-hook battery (VBat) and
   talk battery (VTBat)
• Pulse metering and on-hook transmission
• UL-1950 and MTU compliant on-hook line
   voltage
• 3.3 V compatible logic interface
• Silent or fast polarity reversal
• Programmable Ring-Trip current